Wireless router or residential gateway capable of distinguishing power-sensitive wireless sensors and providing separate treatment thereto

ABSTRACT

Techniques are disclosed for a wireless router or residential gateway to distinguish power-sensitive wireless sensors and provide separate treatments thereto for low power consumption connections. In some embodiments, a network device includes a wireless network circuit, and control circuitry coupled to the network circuit and configured to, upon receipt of a request of connection from a client, identify whether the client is power-sensitive. The network device can further cause, if the client is identified as power-sensitive, the power-sensitive client to connect using a low-power connection while maintaining a regular connection to other regular clients. The low-power connection can be operated on a first channel different from but in a same frequency band as a second channel on which the regular connection is operated.

CROSS-REFERENCE TO RELATED APPLICATIONS AND EFFECTIVE FILING DATEENTITLEMENT

This application is a continuation (CON) application of U.S. Utilitypatent application Ser. No. 14/106,690, entitled “WIRELESS ROUTER ORRESIDENTIAL GATEWAY CAPABLE OF DISTINGUISHING POWER-SENSITIVE WIRELESSSENSORS AND PROVIDING SEPARATE TREATMENT THERETO” (Attorney Docket No.110729-8031.US01), filed Dec. 13, 2013, which claims the benefit of andthe right of priority to U.S. Provisional Patent Application No.61/888,692, entitled “WIRELESS DESIGN FOR USING A ROUTERS OR RESIDENTIALGATEWAY AS SENSOR GATEWAY” (Attorney Docket No. 110729-8031.US00), filedOct. 9, 2013, both of which are hereby incorporated by reference intheir entireties. This application is therefore entitled to an effectivefiling date of Oct. 9, 2013.

This application is related to co-pending U.S. patent application Ser.No. 14/089,651, entitled “WIRELESS SENSOR BASE STATION WITH COEXISTENCEOF MULTIPLE HOMOGENEOUS RADIOS” (Attorney Docket No. 110729-8025.US01),filed Nov. 25, 2013; U.S. patent application Ser. No. 14/089,671,entitled “METHOD AND APPARATUS FOR IMPLEMENTING COEXISTENCE OF MULTIPLEHOMOGENEOUS RADIOS AND TRAFFIC MANAGEMENT THEREIN” (Attorney Docket No.110729-8026.US01), filed Nov. 25, 2013; U.S. patent application Ser. No.14/089,674, entitled “ALIGNMENT OF PACKETS FOR IMPLEMENTING COEXISTENCEOF MULTIPLE HOMOGENEOUS RADIOS” (Attorney Docket No. 110729-8028.US01),filed Nov. 25, 2013; and U.S. patent application Ser. No. 14/089,680,entitled “CHANNEL STEERING FOR IMPLEMENTING COEXISTENCE OF MULTIPLEHOMOGENEOUS RADIOS” (Attorney Docket No. 110729-8028.US02), filed Nov.25, 2013; all of which are hereby incorporated by reference in theirentireties.

TECHNICAL FIELD

The present disclosure relates generally to electronic communications,and more specifically, to controlling radio circuits in wirelesscomputer network systems.

BACKGROUND

With the emerging technologies of wireless networks, embedded systems,and the Internet, there is an ever increasing demand for larger networkbandwidth and higher network speed from all kinds of electronic devicesemployed in various settings, from computing and managing data to onlineshopping and social networking. Electronic and digital content havebecome extensively used in shared, networked environments as compared totraditional stand-alone personal computers and mobile devices. As aresult, data traffic, and especially wireless data traffic, hasexperience an enormous growth.

To accommodate this large need in data traffic, wireless networktechnologies have grown substantially in terms of transmission speed;however, this increase in transmission speed is typically obtained atthe expense of power consumption. Many of electronic devices are mobileor portable devices which rely on limited power resources to operate,and typical, performance-oriented wireless communication techniques mayadversely affect the operational life of these battery powered devices.This is especially true with wireless sensors, such as motion detectors,cameras, pressure and temperature sensors, or carbon monoxide sensors,where these devices are expected to operate on batteries for a long timeand are at idle or asleep most of the time.

Accordingly, it is desirable to provide methods and apparatuses thatreduce power consumption of power-sensitive mobile devices (e.g.,wireless sensors) while still satisfying the need for transmission speedof regular devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The present embodiments are illustrated by way of example and are notintended to be limited by the figures of the accompanying drawings. Inthe drawings:

FIG. 1 is a representative computer network environment within whichsome embodiments may be implemented;

FIG. 2A is an abstract functional block diagram illustrating a wirelessbase station equipped with a coexistence controller in accordance withsome embodiments;

FIG. 2B is a table illustrating example situations where the coexistencecontroller can provide improvements;

FIG. 2C is a table illustrating the upper, center, and lower frequenciesof different Wireless LAN (WLAN) channels in a typical 2.4 GHz frequencyband;

FIG. 2D is a table illustrating example frequencies of differentWireless LAN (WLAN) channels available (e.g., in the United States) in atypical 5 GHz frequency band;

FIG. 3 is a functional block diagram illustrating certain implementationdetails of a specific example of the coexistence controller of FIG. 2Ain accordance with some embodiments;

FIG. 4A and FIG. 4B are abstract diagrams using layered model forillustrating example hierarchical relationships between the coexistencecontroller and other components in the base station of FIG. 2A;

FIG. 5A is a timing diagram illustrating an example of synchronizedoperations of multiple radio circuits as coordinated by the coexistencecontroller in accordance with some embodiments;

FIGS. 5B-5D further illustrate additional details of the synchronizedoperations of FIG. 5A in accordance with some embodiments;

FIG. 6 is a timing diagram illustrating an example of unsynchronizedoperations of multiple radio circuits as coordinated by the coexistencecontroller in accordance with some embodiments;

FIG. 7A is a functional diagram illustrating an additional mode in whichthe present embodiments can operate, in accordance with someembodiments;

FIGS. 7B-7D are functional diagrams illustrating some specific examplescenarios in which the WLAN access point and WLAN station of FIG. 7A maybe operated;

FIG. 8 is a diagram illustrating a probe request procedure on apreferred channel which can be implemented by the coexistence controllerin accordance with some embodiments;

FIG. 9 is a diagram illustrating a probe request procedure on anon-preferred channel which can be implemented by the coexistencecontroller in accordance with some embodiments;

FIG. 10 is an abstract functional block diagram illustrating a wirelessbase station equipped with a coexistence controller implemented in anenvironment with a plurality of wireless sensors in accordance with someembodiments;

FIG. 11 is a timing diagram for handling downlink traffic from the basestation to the wireless sensors of FIG. 10 in accordance with someembodiments;

FIG. 12 is a timing diagram for handling uplink traffic from thewireless sensors to the base station of FIG. 10 in accordance with someembodiments;

FIG. 13 is an abstract diagram illustrating an asymmetrical bufferingstructure or mechanism which can be adopted or controlled by thecoexistence controller in accordance with some embodiments;

FIG. 14 is a flowchart illustrating a method for controlling andcoordinating multiple radio circuits which can be implemented by thecoexistence controller in accordance with some embodiments; and

FIG. 15 is a flowchart illustrating a method for reducing interferenceamong multiple radio circuits which can be implemented by thecoexistence controller in accordance with some embodiments.

FIG. 16 is an abstract diagram illustrating a wireless base station orresidential gateway which implements the fast channel switchingtechniques disclosed herein in accordance with some embodiments;

FIGS. 17A-17B are example timing diagrams respectively illustratingbeacons sent on two separate channels by the base station of FIG. 16 inaccordance with some embodiments;

FIGS. 17C-17D are example timing diagrams for the embodiments where twoor more types of beacon are transmitted on the same channel and where atleast one type of beacon is designated to the power-sensitive clients;

FIGS. 18A-18C are example timing diagrams respectively illustratingswitching channels for beacon in the fast channel switching techniquesin accordance with some embodiments;

FIGS. 19A-19B are example timing diagrams respectively illustratingresource reservation by sensors in the fast channel switching techniquesin accordance with some embodiments;

FIG. 20 is an example timing diagrams illustrating downlink trafficoperations from the base station to the sensors in the fast channelswitching techniques in accordance with some embodiments;

FIGS. 21A-21B are example timing diagrams respectively illustratinguplink traffic operations from the sensors to the base station in thefast channel switching techniques in accordance with some embodiments;

FIGS. 22A-22B are additional or alternative example timing diagramsrespectively illustrating uplink operations in the fast channelswitching techniques in accordance with some embodiments;

FIG. 23 is a flowchart illustrating a method for enabling a base stationto distinguish power-sensitive devices and provide separate treatmentthereto in accordance with some embodiments; and

FIG. 24 is a flowchart illustrating additional or alternative details ofthe method of FIG. 23.

Like reference numerals refer to corresponding parts throughout thefigures and specification.

DETAILED DESCRIPTION

Techniques are disclosed for a wireless router or residential gateway todistinguish power-sensitive wireless sensors and provide separatetreatments thereto for low power consumption connections. In someembodiments, a network device includes a wireless network circuit, andcontrol circuitry coupled to the network circuit and configured to, uponreceipt of a request of connection from a client, identify whether theclient is power-sensitive. The network device can further cause, if theclient is identified as power-sensitive, the power-sensitive client toconnect using a low-power connection while maintaining a regularconnection to other regular clients. The low-power connection can beoperated on a first channel different from but in a same frequency bandas a second channel on which the regular connection is operated.

Among other benefits, the embodiments disclosed herein can increasereduce power consumption of power-sensitive devices (e.g., wirelesssensors) while still satisfying the need for transmission speed ofregular devices by fast channel switching techniques as well as othertechniques disclosed herein.

In the following description, numerous specific details are set forthsuch as examples of specific components, circuits, and processes toprovide a thorough understanding of the present disclosure. Also, in thefollowing description and for purposes of explanation, specificnomenclature is set forth to provide a thorough understanding of thepresent embodiments. However, it will be apparent to one skilled in theart that these specific details may not be required to practice thepresent embodiments. In other instances, well-known circuits and devicesare shown in block diagram form to avoid obscuring the presentdisclosure.

The term “coupled” as used herein means connected directly to orconnected through one or more intervening components or circuits. Any ofthe signals provided over various buses described herein may betime-multiplexed with other signals and provided over one or more commonbuses. Additionally, the interconnection between circuit elements orsoftware blocks may be shown as buses or as single signal lines. Each ofthe buses may alternatively be a single signal line, and each of thesingle signal lines may alternatively be buses, and a single line or busmight represent any one or more of a myriad of physical or logicalmechanisms for communication (e.g., a network) between components. Thepresent embodiments are not to be construed as limited to specificexamples described herein but rather to include within their scope allembodiments defined by the appended claims.

For purposes of discussion herein, “heterogeneous radios” means aplurality of radios or wireless network circuits of different networktechnologies; for example, IEEE 802.11 Wireless LAN (e.g., WiFi),Bluetooth, 2G, 3G, Long Term Evolution (LTE), and Global NavigationSatellite System (GNSS) are all different network technologies than oneanother. Conversely, “homogeneous radios” means a plurality of radios orwireless network circuits of the same network technologies; for example,a plurality of Wireless LAN (WLAN) circuits, although one may operate onchannel 1 of 2.4 GHz frequency band and using IEEE 802.11n protocolwhile another may operate on channel 6 of 2.4 GHz frequency band andusing IEEE 802.11g protocol, are of the same family of WLAN technologyand therefore are homogeneous radios. Some examples of the commonly-seenradios on the 2.4 GHz frequency band may include IEEE 802.11b, IEEE802.11g, or IEEE 802.11n.

System Overview

FIG. 1 is a representative computer network environment 100 within whichsome embodiments may be implemented. The environment 100 includes a basestation 110, a network 120, and a plurality of client devices 130 a-130n.

The base station 110, which is illustrated as operating in “access point(AP)” mode, is coupled together with the network 120 so that the basestation 110 can enable client devices 130 to exchange data to and fromthe network 120. For example, the base station 110 and the network 120may be connected via a twisted pair cabling network, a coax cablenetwork, a telephone network, or any suitable type of connectionnetwork. In some embodiments, the base station 110 and the network 120may be connected wirelessly (e.g., which may include employing an IEEE802.11 wireless network, or a data traffic network based on wirelesstelephony services such as 3G, 3.5G, 4G LTE and the like). Thetechnologies supporting the communications between the base station 110and the network 120 may include Ethernet (e.g., as described in IEEE802.3 family of standards) and/or other suitable types of area networktechnologies. Examples of different wireless protocols in the IEEE802.11 family of standards can include IEEE 802.11a, IEEE 802.11b, IEEE802.11n, IEEE 802.11ac, IEEE 802.11af, IEEE 802.11ah, and IEEE 802.11ad.

Although not shown for simplicity, the base station 110 may include oneor more processors, which may be general-purpose processors or may beapplication-specific integrated circuitry that provides arithmetic andcontrol functions to implement the techniques disclosed herein on thebase station 110. The processor(s) may include a cache memory (not shownfor simplicity) as well as other memories (e.g., a main memory, and/ornon-volatile memory such as a hard-disk drive or solid-state drive. Insome examples, cache memory is implemented using SRAM, main memory isimplemented using DRAM, and non-volatile memory is implemented usingFlash memory or one or more magnetic disk drives. According to someembodiments, the memories may include one or more memory chips ormodules, and the processor(s) on the base station 110 may execute aplurality of instructions or program codes that are stored in itsmemory.

The client devices 130 can connect to and communicate with the basestation 110 wirelessly including, for example, using the IEEE 802.11family of standards (e.g., Wireless LAN), and can include any suitableintervening wireless network devices including, for example, basestations, routers, gateways, hubs, or the like. Depending on theembodiments, the network technology connecting between the clientdevices 130 and the base station 110 can include other suitable wirelessstandards such as the well-known Bluetooth communication protocols ornear field communication (NFC) protocols. In some embodiments, thenetwork technology between the devices 130 and station 110 can include acustomized version of WLAN, Bluetooth, or customized versions of othersuitable wireless technologies. Client devices 130 can be any suitablecomputing or mobile devices including, for example, smartphones, tabletcomputers, laptops, personal digital assistants (PDAs), or the like.Client devices 110 typically include a display, and may include suitableinput devices (not shown for simplicity) such as a keyboard, a mouse, ora touchpad. In some embodiments, the display may be a touch-sensitivescreen that includes input functionalities. Additional examples of thedevices 130 can include network-connected cameras (or “IP cameras”),home sensors, and other home appliances (e.g., a “smart refrigerator”that can connect to the Internet).

It is noted that one of ordinary skill in the art will understand thatthe components of FIG. 1 are just one implementation of the computernetwork environment within which present embodiments may be implemented,and the various alternative embodiments are within the scope of thepresent embodiments. For example, the environment 100 may furtherinclude intervening devices (e.g., switches, routers, hubs, etc.) amongthe base station 110, the network 120, and the client devices 130. Insome examples, the network 120 comprises the Internet.

The Coexistence Mechanism

FIG. 2A is an abstract functional block diagram 200 illustrating awireless base station 210 equipped with a coexistence controller 230 inaccordance with some embodiments. Base station 210 is an example of thebase station 110 of FIG. 1. As shown in FIG. 2A, the wireless basestation 210 includes a plurality of wireless network circuits 220 a-220c and a coexistence controller 230. In accordance with one or moreembodiments, the coexistence controller 230 is coupled to each of thenetwork circuits 220 a-220 c through a coexistence bus 240.

As previously mentioned, many wireless network technologies used inelectronic devices occupy the same or similar frequency band. An exampleof this frequency band is the well-known industrial, scientific andmedical (ISM) radio bands. Take one of the most commonly used of ISMbands, the 2.4 GHz band, for example, the technologies that use thisfrequency band for various kinds of purposes can include Wireless LANand Bluetooth. Several other commonly seen wireless communicationtechnologies also operate at similar frequency bands (e.g., ranging from2.3 GHz to 2.7 GHz); they include LTE Band 40 (TDD-LTE), LTE UL Band 7(FDD-LTE), LTE Band 38 (TDD-LTE), and LTE DL Band 7 (FDD-LTE), just toname a few.

For purposes of discussion herein, assume wireless network circuits 220a-220 c are Wireless LAN circuits operating at a main frequency band of2.4 GHz.

FIG. 2C is a table 204 illustrating the upper, center, and lowerfrequencies of different Wireless LAN channels in a typical 2.4 GHzfrequency band. FIG. 2D is a table 206 illustrating example frequenciesof different Wireless LAN (WLAN) channels available (e.g., in the UnitedStates) in a typical 5 GHz frequency band. As illustrated in FIG. 2C, inthe United States and Canada, there are 11 channels available for use inthe 2.4 GHz Wireless LAN frequency band as defined by IEEE 802.11 familyof standards. In particular, 3 non-overlapping channels (e.g., channels1, 6, and 11) can be selected out of the 11 channels in the IEEE 802.11standards (e.g., IEEE 802.11b) for Wireless LAN access points that arelocated near each other. It is typically recommended that a personordinary skill in the art should use one of the above non-overlappingchannels for each wireless network circuits that operate close by inorder to minimize or reduce the adverse effects of interference.

However, the present embodiments recognize that typically a 50 dBisolation may be necessary to completely or effectively avoid in-devicecoexistence interference when the operating frequencies for differentwireless network circuits are only separated by less than 20 MHz. Thisis especially the case with mobile handset applications where thedevices are of small form factor; devices in such application generallyonly provide 10-30 dB isolation between different wireless networkcircuits. As such, in reality even with transceiving on non-overlappingchannels and, in some instances, employing spectral masks (e.g., atransmit spectral mask for 20 MHz transmission in the 2.4 GHz band asdefined by the IEEE), noise as well as other factors can still causecoexisting wireless network circuits to interfere with each other, andespecially on small form factor devices such as a mobile phone or awireless base station.

For one example, it is observed in the present disclosure that, at leastin the LTE 2.4G ISM band, the lower portion of ISM band is very close tothe LTE TDD Band 40. Therefore, in the case where a single mobile devicewith LTE, WLAN and Bluetooth coexistence, the LTE transmitter may causeinterference to WLAN and/or BT receiver; and similarly, the BT/WLANtransmitter may cause interference to the LTE receiver. For anotherexample, in devices where LTE telephony and Global Navigation SatelliteSystem (GNSS) receiver circuits coexist, the uplink transmissions of LTEBand 13 (e.g., 777-787 MHz) and Band 14 (e.g., 788-798 MHz) can disruptthe working of GNSS receiver using L1 frequency (e.g., 1575.42 MHz). Onereason causing this is that the second harmonic of Band 13 (e.g.,1554-1574 MHz) and second harmonic of Band 14 (e.g., 1576-1596 MHz) areclose to L1 frequency.

Furthermore, the present embodiments recognize that there are severalsituations which can cause interference when two or more radio circuitsconcurrently operate in same or similar frequency band in close physicalproximity. FIG. 2B is a table 202 illustrating example situations wherethe coexistence controller can provide improvements. As shown in table202, when one radio is transmitting, the reception performance of theother radio(s) is desensitized. For purpose of discussion herein, radiocircuits located in close physical proximity, or “collocated,” meansthat the radio circuits are located close to each other enough that atransmission operation on one circuit can adversely affect the receptionoperation on another circuit; for some typical examples, two radiocircuits that are located on the same physical device (e.g., a basestation), or on the same printed circuit board (PCB), are located inclose physical proximity.

It is noted that FIG. 2B is a general representation of the interferingphenomenon which may be caused by concurrent operation of the collocatedradios; in some embodiments, appropriate filtering can also be appliedby a person having ordinary skill in the art so that sensitivity losscaused by different collocated radios transmitting (TX) and receiving(RX) at or near the same time is reduced. In particular, depending onthe frequency band of the channels being used and the type of filtering,the actual severity of the sensitivity loss depicted in FIG. 2B mayvary.

Accordingly, the present embodiments provide an effective mechanism tocoordinate the scheduling of transmission and reception operations ofthe network circuits 220 in order to mitigate in-device interferencecaused by coexistence of wireless network circuits operating at the sameor similar frequency band. In accordance with some embodiments, when twoor more wireless radios may be used in the same band (e.g. 2.4 GHz band,or 5 GHz band) on the same device, the device can employ a coexistencemechanisms (hardware (HW) and/or software (SW)) so that the radios canoperate in same band without desensitizing each other's receivingoperations. The HW mechanism for coexistence can include digitalhardware bus in some embodiments, and can include radio frequency (RF)circuits in other embodiments; in some other embodiments, and the HWmechanism can employ a combination of digital and RF mechanisms.Further, depending on the embodiment, digital HW mechanism may include adirect hardware line connecting accessing mechanism of two chipsets, orit may be hardware lines connecting the accessing mechanism of twohardware blocks inside a chipset. The RF mechanism may include RFfiltering, RF switching, or other suitable RF filters.

More specifically, in one or more embodiments, each of the networkcircuits 220 a-220 c can be assigned a priority, and the coexistencecontroller 230 is coupled to the network circuits 220 a-220 c throughthe coexistence bus 240 to control operations between (or among) thenetwork circuits 220 a-220 c. It is noted that, in some embodiments, itis possible for one or more of the network circuits 220 a-220 c to beassigned with the same priority.

The coexistence controller 230 can selectively adjust one or moretransmission operating parameters of a respective network circuit (e.g.,circuit 220 a) based on a plurality of operating criteria includingnetwork circuit 220 a's priority as compared to other circuits'priorities. The priority each network circuit (e.g., circuit 220 a) canbe predetermined (e.g., by the manufacturer of the base station 210) orcan be dynamically assigned (e.g., by the coexistence controller 230)based on certain priority assigning criteria. The priority assigningcriteria may include the amount of traffic, the type of traffic (e.g.,data, voice, video, sensor applications, etc.), wireless channelconditions each circuit experiences, and/or other suitable factors.

The operating criteria can reflect a variety of considerations such asthe number of client devices (e.g., devices 130, FIG. 1) each networkcircuit handles, the amount of data traffic each network circuit sees,the data rate each network circuit supports, the type of traffic eachnetwork circuit is assigned, the wireless channel condition or noise(e.g., as measured by RSSI or a known matrix rank) each network circuitexperiences, and so forth. According to the present embodiments, theoperating criteria are selected to cause the coexistence controller tocontrol the operations in a way that reduces a probability that networkcircuits 220 a-220 c desensitize one another. In some embodiments, theoperating criteria are selected in a way such that the coexistencecontroller 230 can perform, for example, load balancing and/or frequencyplanning using multiple wireless network circuits (e.g., circuits 220a-220 c) on base station 210.

It is noted that, in the embodiments where the priorities of thewireless network circuits are dynamically assigned, the priorityassigning criteria may be determined in the same way as or in a similarway to the determination of operating criteria by the coexistencecontroller 230.

The transmission operating parameters for a wireless network circuit isthe configurations in which the network circuit uses to transmit data.For example, in some embodiments, the coexistence controller 230 canreduce the transmit power on one wireless network circuit (e.g., circuit220 a) when another wireless network circuit (e.g., circuit 220 b) isreceiving. As previously mentioned, the coexistence controller 230selectively adjusts the transmission operating parameters of the circuit220 a, for example, because the circuit 220 b has a higher priority. Inanother example, circuit 220 a's operating parameters receive adjustmentfrom the controller 230 because operating criteria as determined by thecontroller 230 indicates that the circuit 220 b is connected to (e.g.,and receiving from) a limited power device such as a mobile phone. Theoperating criteria may also reflect that the circuit 220 b is currentlyhandling high priority type of traffic (e.g., such as an image sent froma burglar camera sensor), and therefore the controller 230 adjusts(e.g., suppresses) the transmission operating parameter of the circuit220 a so that circuit 220 a does not interfere with circuit 220 b'sreception.

In additional or alternative embodiments, other transmission operatingparameters that can be adjusted by the coexistence controller 230 caninclude a data rate (e.g., 11 Mbit/s, or 54 Mbit/s) and/or a networkprotocol (e.g., IEEE 802.11a, IEEE 802.11n, IEEE 802.11b, IEEE 802.11ac,IEEE 802.11ah, etc.) at which the respective network circuit operates.In some examples, the transmission operating parameters can also includea channel (e.g., channel 1, channel 6, or channel 11 in WLAN 2.4 GHzfrequency band) on which the respective network circuit operates. Asadditional examples, the channels available in WLAN 5 GHz frequency bandcan include channel 36, channel 100, or channel 161. In someembodiments, the transmission operating parameters can also include afrequency band (e.g., 2.4 GHz, 5 GHz, etc.) in which the respectivenetwork circuit operates. Other known configuration adjustments such asmodulation or phase adjustments can also be included in the list oftransmission operating parameters which the coexistence controller 230can adjust. In some embodiments, proper RF filtering can be applied toreduce the effect of interference. In some of these embodiments, when RFfiltering is applied, proper channel selection may be done by softwarepart of the coexistence mechanism to better utilize the RF filtering.

The coexistence bus 240 may be used by the coexistence controller 230 toschedule or coordinate transmission and reception to avoid receptiondesensitization. The coexistence bus 240 can be implemented in forms ofa serial bus, several dedicated buses, or other suitable forms such as anetwork. Specifically, depending on the embodiment, the coexistencemechanism may be software only, hardware only, or a combination of both.Examples of hardware-based coexistence mechanisms may include a hardwarebus, a modified radio frequency (RF) frontend, and/or other suitableimplementations. Examples of software-based coexistence mechanisms maybe located at different layers of networking including, for example, thePHY layer, the MAC layer, and/or the IP layer.

In some specific implementations, the coexistence bus 240 together withthe coexistence controller 230 can employ coexistence mechanisms similarto the IEEE 802.15.2 Wireless LAN (WLAN)-Bluetooth (which areheterogeneous radios (e.g., operating) coexistence mechanisms forimplementing/coordinating coexistence of homogeneous radios (e.g.,WLAN-WLAN) operating at the same or similar band; however, it is notedthat the standard IEEE 802.15.2 coexistence mechanism is specific toWLAN-Bluetooth coexistence applications, and that suitable modifications(e.g., such as those described herein) may be necessary for homogeneousradios application. FIG. 3 is a functional block diagram illustratingcertain implementation details of the specific embodiment of thecoexistence controller of FIG. 2A employing a modified IEEE 802.15.2coexistence mechanism in accordance with some embodiments.

Depending on the embodiments, either the collaborative or thenon-collaborative mechanisms (as specified in IEEE 802.15.2 standards)or both may be adapted for use with the coexistence controller 230. Asillustrated in FIG. 3, the collaborative coexistence mechanism of IEEE802.15.2 is modified (e.g., which can be implemented by the coexistencecontroller 230, FIG. 2A) to perform packet traffic arbitration forcoexistence of homogeneous radios (e.g., WLAN-WLAN) applications. It isnoted that more details of the Packet Traffic Arbitration (PTA)mechanisms can be found in Clause 6 of the 802.15.2 RecommendedPractices.

Of course, a person having ordinary skill in the art will know thatother standard or non-standard coexistence mechanisms (e.g., which maybe developed for heterogeneous radio coexistence such as WLAN,Bluetooth, and LTE) may also be modified and applied to homogeneousradio coexistence (e.g., WLAN to WLAN) in similar fashion as disclosedherein.

FIG. 4A and FIG. 4B are abstract diagrams using layered model 400 forillustrating example hierarchical relationships between the coexistencecontroller 230 and other components in the base station 210 of FIG. 2A.The model 400 generally follows the naming conventions of the well-knownopen systems interconnection (OSI) model, as standardized in ISO/IEC7498-1 by the International Organization for Standardization (ISO). Forpurposes of discussion herein, the media access (MAC) layer sits betweenthe network layer (layer 3 of OSI model) and physical (PHY) layer(layer 1) and is a sub-layer of the data link layer (layer 2) whichprovides addressing, channel access control, as well as other suitablefunctionalities. It is noted that model 400 is provided herein to enablefurther understanding of the present embodiments; and that other models(e.g., TCP/IP model) can be used and/or modified for implementing thepresent embodiments.

As illustrated in FIGS. 4A-4B, in accordance with one or moreembodiments, the coexistence controller 230 (FIG. 2A) can function as anadditional layer (labeled as MAC2) on top of the MAC layer of anexisting wireless network circuit so that radio circuit that are readilydesigned and available on the current market can be adopted (e.g., intothe base station 210, FIG. 2A) as modules in order to increasereusability and save redesign cost. Notably, FIG. 4A illustrates a modelthat employs a coexistence bus to coordinate the radios at MAC layer; incomparison, the model illustrated in FIG. 4B does not employ thecoexistence bus, but it utilizes RF filters to aid the coexistencemechanism located on the MAC2 layer. In some embodiments, the MAC2 layermay include link aggregation mechanisms to aggregate the links at thelower layer (e.g., the two MAC-layer links as shown in FIG. 4B).

The coexistence bus 240 (FIG. 2A) can function as a coordinationmechanism coupled to the MAC layer of the network circuits. The bus 240can be employed by the coexistence controller 230 to communicate andcontrol each of the network circuits 420. Accordingly, the networkcircuits can each include individual media access control (MAC) layerand physical (PHY) layer circuitry, such as MAC and PHY layers 420illustrated in FIG. 4. In other words, in some embodiments of the basestation 210, there can be separate and independent MAC engines for thenetwork circuits 220 a-220 c (FIG. 2A) with coexistence bus 230 and aMAC2 layer above (e.g., where coexistence controller 240 resides) formanagement. In some embodiments, either the MAC or the MAC2 layer or thetwo together can perform aggregation, encryption, decryption, and/orother timing critical tasks. In some embodiments, the coexistencecontroller 230 can manage network data traffic from a select number ofnetwork circuits 220 a-220 c so as to aggregate a bandwidth of theselected number of network circuits (which is discussed in more detailsbelow). Examples of aggregation can include Aggregation of MAC protocoldata units (AMPDU) and Aggregation of MAC service data units (AMSDU).Example of encryption can include the Advanced Encryption Standard(AES), Wired Equivalent Privacy (WEP), Temporal Key Integrity Protocol(TKIP), and the like.

With continued reference to FIG. 2A, in some embodiments, the operationcontrols (e.g., operating parameter adjustments) by the coexistencecontroller 230 are independently performed to each of the networkcircuits 220 a-220 c, so that the operating parameters of each circuit(e.g., circuit 220 a) can be fine-tuned by the coexistence controller230 individually and without necessarily affecting other networkcircuits coupled to the same coexistence bus 240.

In combination of the above, one or more embodiments of the coexistencecontroller 230 can implement techniques that reduce interference, suchas reducing transmission power, changing the channel, or disablingtransmission of selected network circuits based on workload, type oftraffic, priority of the network circuits and their connected clients(e.g., by whether they are power consumption sensitive), type of thedata traffic, channel noise observed by the radio antennas, or othersuitable factors that are experienced by the network circuits 220 a-220c. In some implementations, the operations between the network circuits220 a-220 c are controlled by the coexistence controller 230 in a waysuch that the network circuits 220 a-220 c can transmit and receive dataat or near the same time. For example, the wireless network circuit 220a can be transmitting on channel 6 of 2.4 GHz frequency band at anattenuated power level while the wireless network circuits 220 b and 220c can be respectively receiving on channel 1 and 11 of 2.4 GHz frequencyband. In some embodiments, and in particular those embodiments thatequip radios operating in the 5 GHz frequency band, proper filtering canalso be adapted by the coexistence mechanisms. Some embodiments of thecoexistence mechanism can adapt RF filtering or other frontendtechniques to aid the coexistence mechanisms in reducing interferenceand discretization from one radio to other.

The configuration of base station 210 shown in FIG. 2A and layered model410 shown in FIG. 4 are merely examples. Base station 210 may includeany suitable numbers of network circuits 220 a-220 c, more than onecoexistence controller 230, and/or additional processing units coupledto the coexistence bus 240 to perform coordination/control operations.Furthermore, the coexistence controller 230 may be integrated into othersuitable kinds of computing devices including, for example, acceleratedprocessing units (APUs), field-programmable gate arrays (FPGAs), digitalsignal processors (DSPs), or other devices with microprocessors.

Alignment of Packets

FIG. 5A is a timing diagram 500 illustrating an example of synchronizedoperations of multiple radio circuits as coordinated by the coexistencecontroller in accordance with some embodiments, and FIG. 6 is a timingdiagram 600 illustrating an example of unsynchronized operations ofmultiple radio circuits as coordinated by the coexistence controller inaccordance with some embodiments. The coexistence mechanisms, which canbe employed by the coexistence controller 230 (e.g., in concert with thecoexistence bus 240) of FIG. 2A for implementing various homogeneousradio coexistence functionalities disclosed herein, are discussed infuller detail below and with continued reference to FIG. 2A.

As previously mentioned, according to some embodiments, a combination ofa coexistence bus (e.g., bus 240) connecting the lower MAC layers with amanaging coexistence controller (e.g., controller 230) in MAC2 layer(and for some embodiments, in higher layers) may be deployed toimplement the present disclosed embodiments. Depending on theimplementation, one radio circuit (e.g., circuit 220 a) or a group ofradio circuits may be given the highest priority and act as master, orall radio circuits (e.g., circuit 220 a-220 c) can have similarpriorities. Additionally or alternatively, priorities of the radios canbe changed dynamically (e.g., depending on workload and other operatingcriteria) or can be changed over time (e.g., using time sharingmechanisms, round robin, or other suitable multi-access protocols).Depending on the embodiment, the coexistence mechanisms can involve onlythe MAC2 layer, only the upper MAC layer, or a suitable combination ofboth.

Although one benefit of the present embodiments is to avoid receptiondesensitization, other operating criteria (e.g., type of traffic, orfairness) may be taken into consideration by the coexistence controller230 as well. In one example, the coexistence mechanism (e.g., asimplemented by the coexistence controller 230 and the coexistence bus240) can assure that all wireless network circuits receive at least achance to transmit; other operating criteria can include fairness amongall the radios for transmission, or the operating criteria can include astarvation policy. In some embodiments, quality of service (QoS) can betaken into account when the coexistence mechanism determines which radiocircuits gets to transmit and when. In some embodiments, even whenduring the period when a radio circuit is suppressed or disabled by thecoexistence mechanism, certain short transmission of acknowledge (ACK)packets can be allowed; this technique can be helpful in some caseswhere channel coding is used.

Also, it is noted that in some mechanisms the transmission suppressionor suspension may not be required due to other suitable software andhardware techniques used.

As such, according to some embodiments, the coexistence mechanism cansynchronize the transmitting and receiving operations to increase ormaximize the total wireless network's throughput (TPUT) or bandwidth.Such synchronized operations are illustrated in diagram 500. In diagram500, all transmitting operations and receiving operations aresynchronized among all wireless network circuits 220 a-220 c so that thecircuits 220 a-220 c only perform either transmission or reception atany given moment of time. This technique can avoid the desensitizationcaused by different homogeneous radios transmitting and receiving at thesame time, such as illustrated in table 202 of FIG. 2B. It is noted thatAMPDU, AMSDU, or a combination of both may be used in downlink datapackets. For the example that is shown in diagram 500, the downlink (DL)data packets are illustrated as comprising DL AMPDU and Single MPDU.Optionally, Request to Send (RTS) and Clear to Send (CTS) handshakepackets can be exchanged between the sender (e.g., client devices 130,FIG. 1) and the base station 210 before the data transmission/receivingoperations. In addition or as an alternative to increasing throughput,the coexistence mechanism may be used to coordinate the radios toachieve better delay requirement or other quality of service (QoS)metrics for one or more of the radios.

More specifically, as shown in FIG. 5A, the coexistence mechanism canalign the downlink packet transmissions (or receiving operations) of anumber of selected wireless network (e.g., WLAN) circuits operating ondifferent channels in the same frequency band for synchronizedoperations. In some embodiments, the packets received by different radiocircuits need to have the same duration in the downlink, and in suchembodiments, frame padding may be performed by the coexistencecontroller 230 to make data packets (e.g., received on the downlink)among the radio circuits 220 a-220 c become the same size.

FIGS. 5B-5D further illustrate additional details of the synchronizedoperations of FIG. 5A, including some examples of the padding techniqueswhich can be utilized by the coexistence mechanism, in accordance withsome embodiments.

Continuing with the example of FIG. 5A where the AMPDU is used indownlink (DL) data packets, diagram 502 of FIG. 5B depicts a typicalstructure of the AMPDU subframe. In accordance with one or moreembodiments, each AMPDU subframe can include an MPDU delimiter, whichcan optionally be followed by an MPDU. Additionally, zero lengthdelimiter can also be used. Although not shown in FIG. 5B forsimplicity, the “length” field of the MPDU delimiter can includedifferent number of bits based on the type of IEEE 802.11 packet orother suitable requirements as the network technology being used sorequires.

In the example shown in diagram 504 of FIG. 5C, one or more zero lengthdelimiters are added to make AMPDUs of different homogeneous radiocircuits (e.g., IEEE 802.11n versus IEEE 802.11ac, as illustrated inFIG. 5C) the same size in order to align the packets. It is noted that,in diagram 504, the delimiters are added at the end of the frames;however, other suitable locations may be used. For example, in diagram506 of FIG. 5D, the zero length delimiters are shown to be used in themiddle of the packets.

Further, the coexistence mechanism can also transmit the uplink responsepackets simultaneously or nearly simultaneously (e.g., within an errormargin as defined by the IEEE 802.11 specification), such as shown inthe diagram 500 of FIG. 5A. Some embodiments of the coexistencemechanism can also employ different modulations and/or can includedifferent number of bytes in a PHY or MAC payload in order to transmitand/or receive different packets on different channels.

As an additional or alternative embodiment to synchronized transmittingand receiving operations, the coexistence mechanism can employunsynchronized operations as well. In unsynchronized operations,transmitting or receiving operations on different network circuits (andpreferably each on different channels) can be prioritized by thecoexistence controller 230 using the aforementioned operating criteria(e.g., based on the nature of the data traffic, fairness, starvationavoidance policies (which may be based on different hierarchies ofpayment plans, for example), and so forth) in manners discussed above.For example, as shown in diagram 600 of FIG. 6, radio circuit 2'stransmission is delayed or deferred because radio circuit 1 is alreadyreceiving (e.g., because radio circuit 1 has higher priority). Notablyin the example diagram 600, radio 1 can still transmit the ACK packetsduring radio 3's receiving operation. This may be because thecoexistence controller 230 determines that the interference caused bythe transmission of ACK packets may be tolerated (e.g., because thetransmission is short, because the transmission can be performedsuccessfully at an attenuated power level, or because other suitablereasons such as those discussed above), or simply because radio 1 has ahigher priority than radio 3.

FIG. 7A is a functional diagram 700 illustrating an additional mode inwhich the coexistence controller 210 (FIG. 2A) can operate, inaccordance with some embodiments. As illustrated in diagram 700, thecoexistence controller 210 (e.g., as implemented in a base station suchas station 110, FIG. 1) can coordinate with a client (e.g., clientdevices 130 a-130 n) with another plurality of wireless network circuitsin a way such that a respective network circuit on the network devicecommunicates with a corresponding network circuit on the client using auniquely designated channel.

For example, if a Wireless LAN access point is equipped with 3 wirelessnetwork circuits, and if a client device is also equipped with 3wireless network circuits, then the coexistence controller 230 cancoordinate (e.g., using suitable standard or customized protocols) withthe client device so that each radio circuit on the access point cancommunicate with a corresponding radio circuit on the client device on achannel different than the others such that interference can be reducedwhile increasing the bandwidth. In other words, a first wireless networkcircuit on the access point can use channel A exchange data with a firstwireless network circuit on the client device, a second wireless networkcircuit on the access point can use channel B exchange data with asecond wireless network circuit on the client device, and so forth.

It is noted that the client may also have to implement the coexistencemechanisms disclosed herein in order to perform this kind of channelcoordination/bandwidth aggregation/interference reduction techniqueswith the base station.

Furthermore, in some examples where a client device with multiple radiosand implementing the coexistence mechanisms disclosed herein isconnected to the base station 210, the coexistence controller 230 canreorder the received frames from the various connected client devicesand deliver them in sequence to the higher layer (e.g., the IP layer),in addition to functionalities already mentioned above. In someembodiments, the coexistence controller 230 can be coupled to a reorderbuffer (not shown for simplicity) for performing the reordering tasks.

Also, since the embodiments of the coexistence controller 230 cancontrol multiple Wireless LAN radio circuits separately, in someimplementations, a select number of radio circuits may be operated toact as access points (APs) while another selected number of radiocircuits may be operated to act as clients. This technique may be usefulfor range extension or other suitable purposes.

Optionally, the coexistence controller 230 can implement WiFi Direct,Peer-to-Peer, or any other IEEE 802.11 or WiFi optional features usingone or more of the radio circuits equipped on the base station 210.

FIGS. 7B-7D are functional diagrams illustrating some specific examplescenarios in which the WLAN access point and WLAN station of FIG. 7A maybe operated. In FIGS. 7B-7D, the WLAN station connected to the WLAN APmay itself function as an AP for other wireless stations.

Channel Steering

In addition or as an alternative to the aforementioned functionalities,some embodiments of the coexistence controller 230 can dynamicallydetermine (e.g., during the base station 210's normal operations andbased on operating criteria) and distribute the connected client devices130 onto different wireless network circuits 220 a-220 c and/ordifferent channels. For purposes of discussion in this section, it isassumed that each of the radio circuits operates on a different channelin the same frequency band; however, different combinations of switchingnetwork circuits and/or channels can be implemented or executed by thecoexistence mechanism disclosed herein.

More specifically, the coexistence mechanisms (e.g., as implemented bythe coexistence controller 230 and the coexistence bus 240) canassociate the client stations to the base station 210 onto differentchannels. Because the base station 230 includes a plurality of wirelessnetwork circuits each capable of operating on a different channel, inone or more implementation, the multi-channel base station 210 canemploy the coexistence controller 230 to steer client devices ontodifferent channels based on operating criteria (e.g., such as thosementioned above). In other words, the coexistence controller 230 candecide which client station is to be connected to which network circuit(and its associated channel) based on the operating criteria.

In addition or as an alternative to those aforementioned operatingcriteria, some examples of the operating criteria can include: loaddistribution and balancing among the channels, any throughputrequirement, any QoS requirement (e.g., delay, jitter, packet errorrate, throughput specification, etc.), any interference from otherradios in each channel, any interference from other Wireless LAN orother radios (e.g., operated by other nearby base stations or clientswith overlapping basic service set identifications (BSSID)), anyinterference from non-WLAN-related devices (e.g., microwave oven), andso forth.

In some embodiments, the coexistence controller 230 is situated on topof MAC layer (e.g., as the MAC2 layer such as illustrated in FIGS. 4Aand 4B) for management of the radio circuits, which each may includetheir own MAC and PHY circuitry. It is noted that other layers in thenetwork stack (e.g., other layers in the OSI model) can also be used formanagement of the multiple wireless network (e.g., WLAN) circuits.

According to one or more embodiments, the coexistence controller 230 canalso enforce the selection by making sure the client device cannotassociate itself on any other unauthorized channels. In some additionembodiments, the coexistence controller 230 can function in a way suchthat the communication interface to an upper layer (e.g., the networklayer or IP layer in the OSI model) remains the same. It is noted that,after a client device is associated to the base station 210, thecoexistence controller 230 may need to pass the data packets designatedfor a client device to the MAC layer of a corresponding radio circuitthat services the channel with which the client device is associated orassigned.

Moreover, after a client device is connected to a network circuit andassociated with a channel, the coexistence controller 230 can move theclient device from one channel to another channel when such move becomesdesirable. For example, if the data traffic workload aggregated from allclient devices connected to one network circuit exceeds or about toexceed the service capacity of the network circuit, then the coexistencecontroller 230 can selectively move some of the connected clients toanother wireless network circuit. For another example, if theinterference on a channel (e.g., as observed by the network circuitoperating on the channel) increases to level that exceeds a maximumthreshold (e.g., so that current connected client devices may not beserviced properly), then the coexistence controller 230 can selectivelymove some of the connected clients to another wireless network circuit.For some embodiments, if the channel condition on another channelbecomes better than the current channel (e.g., because removal of aninterference source), then the coexistence controller 230 canselectively move some of the connected clients to another wirelessnetwork circuit. In some embodiments, typical channel switchannouncement may be used to move the client devices from one channel toanother channel. Specifically, in some embodiments, channel switchannouncement or other methods in IEEE 802.11h may be used to move astation from one channel to another channel. It is noted that techniquessimilar to those described in IEEE 802.11h can be adapted by someembodiments of the present disclosure to resolve interference issuesintroduced by the use of IEEE 802.11a/n/ac in some locations, and inparticular for military, weather radar systems or other suitable devicessuch as medical devices.

In addition, in some other embodiments, the AP may disassociate orde-authenticate selected clients on a channel without using a channelswitch announcement. The reason for not using a channel switchannouncement may be, for example, lack of support on the client side. Insome other examples, the AP may decide not to use a channel switchannouncement due to lack of time because the AP may need to move someclients away from a certain channel as soon as possible.

Also, some embodiments of the base station 210 can keep/migrate all thestate information (e.g., network settings, hardware configurationinformation, etc.) for the client device when the client device isswitched from one channel to another to minimize the switch time.

FIG. 8 is a diagram 800 illustrating a probe request procedure on apreferred channel which can be implemented by the coexistence controller230 in accordance with some embodiments, and FIG. 9 is a diagram 900illustrating a probe request procedure on a non-preferred channel whichcan be implemented by the coexistence controller 230 in accordance withsome embodiments.

With continued reference to FIG. 2A, some specific examples forimplementing the channel steering techniques are now discussed. In theseexamples where the wireless network circuits are IEEE 802.11 WLANcircuits, the following management frames are some examples among theframes that can be used by the coexistence controller 230 for thechannel steering techniques: Probe Request, Probe Response,Authentication, De-authentication, Association Request, AssociationResponse, Re-association Request, Re-association Response, andDisassociation. The following examples are described using IEEE 802.11terminologies; however, it is noted that these examples are providedherein to provide a better understanding of the coexistence mechanisms,and that neither these IEEE 802.11 management frames nor IEEE 802.11WLAN circuits are necessary in practicing the present embodiments.

As mentioned, the coexistence mechanism disclosed herein can steer aconnecting client to a specific channel/network circuit at time ofassociation, and can also steer a client to another specificchannel/network circuit after the device is already connected.

Accordingly, in some embodiments, when a client device tries to connectwith the base station 210, the coexistence mechanism may choose not torespond to a probe request, authentication request, or associationrequest from the client device on a non-preferred channel. Morespecifically, assuming channel B is a preferred channel, and channel Ais a non-preferred channel, when the client device sends a probe requestto the base station 210 on a non-preferred channel A, the coexistencecontroller 230 can make a determination so as to ignore the proberequest on the non-preferred channel A. On the contrary, when the clientdevice sends a probe request on a preferred channel B, the coexistencecontroller 230 can respond to that probe request so that the clientdevice can connect to the base station 230 on the preferred channel B.Additionally, the coexistence controller 230 can choose to cause thebase station 210 not to broadcast the service set identification (SSID)on a channel that is already at its maximum capacity so as to avoid aclient device from requesting association to a non-preferred channel. Itis noted that similar mechanisms depicted in FIGS. 8-9 can be applied toAuthentication Request, Association Request, or other forms of knownpre-association or post-association requests.

Additionally or alternatively, it is recognized in the presentdisclosure that a client device may still attempt to associate with thewireless base station 210 on the non-preferred channel instead ofswitching to other channels even when the client device receives noresponse. As such, some embodiments of the wireless base station 210 mayselect a maximum number of requests to ignore; for example, the basestation 210 can ignore the first M association requests on thenon-preferred channel, but if the client device continues and try forthe (M+1)th time on the same non-preferred channel for association, thenthe base station 210 can associate the client device on thenon-preferred channel in order to avoid a complete denial of service tothat client device. In this particular example, the coexistencecontroller 230 may choose to then move the client device from theassociated non-preferred channel to a preferred one after theconnection.

An example association procedure in which the client device associateswith the base station 210 via a wireless signal (e.g., such as a ProbeRequest) on a preferred communication channel is depicted in diagram800. During normal operations, the client device may initiate a ProbeRequest at time t0 on a preferred channel of the base station 210. Then,the Probe Request is received by the base station 210 at time t1.

After receiving Probe Request at time t1, the base station 210determines whether the Probe Request is received on a preferred channel.In the illustrated example of diagram 800, because the Probe Request isreceived on the preferred communication channel of the base station 210(e.g., as determined by the coexistence controller 230), the basestation 210 transmits a responsive signal (e.g., a Probe Response) onthe preferred communication channel at time t2. The Probe Response onthe preferred channel is received by the client device at time t3.Thereafter, the Wireless LAN circuit located on the base station 210become a candidate to the client device for association and availablefor data communication.

An example association procedure in which the client device associateswith the base station 210 via a wireless signal (e.g., such as a ProbeRequest) on a non-preferred communication channel is depicted in diagram900. During normal operations, the client device may transmit a ProbeRequest on a non-preferred communication channel of the base station 210at time t0. The base station 210 receives the Probe Request on thenon-preferred communication channel from the client device at t1.

Then, according to some embodiments, the base station 210 can choose toignore the Probe Request, thereby triggering the client device totransmit another Probe Request on another communication channel whichmay be the base station 210's preferred channel. It is noted that, whilemany Wireless LAN clients available on the current market may try tosense probe requests on another channel when they do not hear proberequests on one channel, some embodiments of the client device disclosedherein may also implement the coexistence mechanisms so that the clientdevice would switch the channel on which it sends the Probe Requestbased on prior information. In some embodiments, the base station 210may also choose to use suitable communication methods to notify theclient device of the base station 210's currently preferred channel(s).

In the example illustrated in diagram 900, the client device switchesthe channel twice and transmits a Probe Request on the preferredcommunication channel of the base station 210 at time t4. This ProbeRequest is received by the base station 210 at time t5. In response, attime t6, the base station 210 transmits a Probe Response on thepreferred communication channel to the client device, and the ProbeResponse is received by the client device at time t7. Thereafter, theWireless LAN circuit located on the base station 210 become a candidateto the client device for association and available for datacommunication.

Moreover, when a communication channel to which the client device isalready connected becomes a non-preferred channel, the coexistencecontroller 230 can steer a client to another specific channel/networkcircuit. More specifically, in some examples, the base station 210 cansend a De-authentication message at a proper time (e.g., when timecritical traffic exists or is anticipated), and when the client devicetries to re-authenticate, the base station 210 does not respond to theclient device's Probe Requests to access the base station 210. In thisway, the client device can be triggered to attempt to re-authenticate onanother channel which may be the base station 210's preferred channel.

In additional or alternative embodiments, the coexistence controller canalso move the client device from a non-preferred channel to a preferredchannel using one or more suitable communication protocols (e.g.,channel switching procedures as specified in the IEEE 802.11h and/or theIEEE 802.11v directed roaming protocol). Also, in some embodiments, thecurrent connection between the client device and the base station 210can be maintained (e.g., without termination), and the client device canbe moved to the preferred channel when the next time it connects to thebase station 210.

The following are some examples of how the coexistence controller 230may group the client devices. In all examples, the base station 210 isequipped with three wireless network circuits, one operating on channelA, another one operating on channel B, and the third one operating onchannel C. Also, all of the wireless network circuits are operating atthe same frequency band in these examples.

In one example, channel C has the best condition, and channel B has theworst condition. As such, because channel B experiences a lot of noise,the coexistence controller 230 can choose to move all client devicesthat are without delay or performance requirements to channel B. ChannelC is the best channel, and the coexistence controller 230 can move thosetraffic types with the most stringent performance requirement (e.g.,VoIP or Video Conference applications) to channel C. Depending on thechannel A's condition, channel A can maintain a few devices withstringent performance requirement as well.

In another example, the coexistence controller 230 can group the clientdevices based on their traffic types (e.g., such as VoIP,Video-on-Demand, or other applications which only request best effort).

In yet another example, if all channels have similar capacities andsimilar conditions, then the coexistence controller 230 can combine andmix client devices with different type of traffic onto each channel forload balancing.

In an additional example, the coexistence controller 230 can group theclient devices based on their respective power requirements so thatthose client devices which are limited in power resource (e.g., runningon batteries) can transmit at a different power level (e.g., at a lowerdata rate) than those devices which are unlimited in power resource(e.g., plugged into an electrical outlet).

In other examples, the coexistence controller 230 can group the clientdevices based on their similarity in capabilities. For example, deviceswith multi-user multiple-input and multiple-output (MU-MIMO)capabilities can be grouped together on a channel different than theother devices.

Home Wireless Sensor Application

FIG. 10 is an abstract functional block diagram 1000 illustrating awireless base station 1010 equipped with a coexistence controller 1030implemented in an environment with a plurality of wireless sensors 1070a-1070 n in accordance with some embodiments. The base station 1010includes wireless network circuits 1020 a and 1020 b, both coupled to acoexistence controller 1030 via a coexistence bus 1040. In someembodiments, the wireless circuits 1020 a and 1020 b may be differentdiscrete components, or they may be integrated into one or morechipsets.

A residential gateway 1050 is coupled to the base station 1010 toprovide data communication services (e.g., to the Internet) to the basestation 1010 and its clients (e.g., sensors 1070). The gateway 1050 maybe coupled to the base station 1010 via, for example, a wireless networkcircuit 1060 of the gateway 1050. For purposes of discussion herein,assume the network circuit 1060 is connected to the base station 1010via the network circuit 1020 a. Examples of the residential gateway 1050may include a cable modem, a digital subscriber line (DSL) modem, asatellite modem, and the like. Although not shown for simplicity, thegateway 1050 can also be coupled to data traffic networks based onwireless telephony services (e.g., such as 3G, 3.5G, 4G LTE, and thelike) in providing data services to the base station 1010.

The wireless sensor 1070 a-1070 n are sensors that are typically placedin a residential or an office environment. The sensors 1070 a-1070 ninclude wireless network capabilities for coupling to and communicatingwith the base station 1010. For purposes of discussion herein, assumethe wireless sensors 1070 a-1070 n are connected to the base station1010 via the network circuit 1020 b. Some examples of the wirelesssensor 1070 a-1070 n include door sensors, motion sensors, surveillancecameras, fire/smoke detectors, Carbon monoxide (CO) detectors, garagedoor openers, thermostats, cable television control boxes, gas meters,and so forth. Although not necessarily, one or more sensors of thesensors 1070 a-1070 n may typically have limited power resources (e.g.,running only on batteries).

The base station 1010 is similar to the base station 210 of FIG. 2A, andin this specific settings, can be a base station designated for thewireless sensors including, for example, a home security console devicesuch as provided by Comcast Corp., ADT Corp, or AT&T Corp. Asillustrated in diagram 1000, the base station 1010 includes at least twowireless network circuits 1020 a and 1020 b, circuit 1020 a beingcoupled to the gateway 1050 and circuit 1020 b being coupled to thewireless sensors 1070 a-1070 n. In one or more embodiments, the basestatin 1010 functions as a repeater which can pass data traffic (e.g.,control commands) received from the gateway 1050 to the wireless sensors1070 a-1070 n, and can pass data traffic (e.g., captured images, oralarm signals) received from the wireless sensors 1070 a-1070 n to thegateway 1050. Among other reasons, because the power limitation andother characteristics specific to the wireless sensors 1070 a-1070 n, itwould be beneficial to separately connect the sensors 1070 a-1070 n to aseparate wireless network circuit than that is used to connect theresidential gateway 1050.

However, as previously mentioned, it is recognized that interference anddesensitization can happen in settings where more than one wirelessnetwork circuits transmitting and receiving in the same frequency bandand in close physical proximity. Specifically, when the base station1010 is transmitting data to the wireless sensors 1070 a-1070 n usingcircuit 1020 b, which can cause the reception of circuit 1020 a tobecome desensitized, if the gateway 1050 attempts to communicate withthe base station 1010 during the circuit 1020 b's transmission, the basestation 1010 can miss the data sent from the gateway 1050, and thereforethe gateway 1050 may have to retransmit. Luckily, the gateway 1050typically does not have power resource concerns.

Similar situation can take place when the base station 1010 istransmitting data to the gateway 1050 using circuit 1020 a, which cancause the reception of circuit 1020 b to become desensitized, and if thegateway 1050 attempts to communicate with the base station 1010 duringthe circuit 1020 a's transmission, the base station 1010 can miss thedata sent from the wireless sensors 1070 a-1070 n, and therefore thewireless sensors 1070 a-1070 n may have to retransmit. However, this maybe undesirable because the wireless sensors 1070 a-1070 n may have powerresource concerns, and retransmission can adversely impact the operatinglifespan of the sensors 1070 a-1070 n.

Existing solutions can include using sectional antennas and creatingenough shielding among the radio circuits. However, because the wirelesssensors can be deployed in any location around the physical environment,it is desirable to have omnidirectional antennas so that the wirelesscommunication coverage of the base station can be maximized.

Accordingly, in some embodiments, the coexistence controller 1030 cancause the wireless circuits 1020 a and 1020 b to operate in ways that donot cause interference or desensitization to one another. Morespecifically, the coexistence controller 1030 can utilize thecoexistence mechanisms mentioned above, for example, to give priority tothose data communications from the various wireless sensors 1070 a-1070n by selectively suppressing the transmitting operations of the wirelessnetwork circuit 1020 a during the receiving operations of the wirelessnetwork circuit 1020 b. For example, the coexistence controller 1030 cansuppress the transmission communication by disabling, postponing,attenuating the power level used in, reducing transmission rate of, orapplying any other operating parameter adjustment techniques discussedherein onto, the transmission operations. In this way, the coexistencecontroller 1010 is able to suppress the transmitting operations of thenetwork circuit 1020 a in a way that maintains integrity of receivingoperations of the network circuits 1020 b (e.g., so that the receivingis not disrupted or corrupted). It is noted that some embodiments of thewireless network circuits 1020 a-1020 b operate on different channels(e.g., channels 1 and 6).

In some additional embodiments, the coexistence controller 1030 isconfigured to allow the network circuit being suppressed, during thesuppression, to respond to high priority communication after everypredetermined time period. For example, the Wireless LAN circuit beingsuppressed may still be able to respond to management packets.

In some embodiments, the coexistence controller 1030 can also operatethe wireless network circuit 1020 b in a way that reduces powerconsumption of the wireless sensors 1070 a-1070 n. For example, whilethe operations of the wireless network circuit 1020 a remains unaffected(e.g., which can be optimized for speed performance, or otherconsiderations), the operations of the wireless network circuit 1020 bcan utilize various parameters and options that are available in theIEEE 802.11 standards to save power on the sensors 1070 a-1070 n.

Specifically, there are two example power saving techniques existing inthe IEEE 802.11 family of standards which can be adapted by thecoexistence controller 1030 for reducing the power consumption on thewireless sensors 1070 a-1070 n. One example is known as the power savingpoll (PS-Poll); the other example is known as the unscheduled automaticpower save delivery (UAPSD).

In other embodiments, the coexistence controller 1030 can also utilizecustomized protocols or modified versions of standard protocols tocommunicate with the wireless sensors 1070 a-1070 n in order to assistthe sensors 1070 a-1070 n in reducing power consumption. For example,the coexistence controller 1030 can cause wireless network circuit 1020b to operate on a modified version of wireless network protocol that hasrelaxed link upkeep standards, such as relaxing an ACK packet's responsetime from 1 milisecond to 2 seconds.

In addition examples, the wireless network circuit(s) (e.g., circuit1020 b) that connects to the wireless sensors 1070 a-1070 n can employpower saving mechanisms such as described in the IEEE 802.11ah standardsin various frequency bands (e.g., 2.4 GHz, 5 GHz, or other bands). Oneor more embodiments can support client devices or sensors that cantransmit traffic indication maps (TIM), and the coexistence controller1030 can arrange traffic scheduling and give priority to a respectivewireless circuit based on the received TIM information.

Further, for the client devices or wireless sensors that do not have TIMcapacity, when the base station 1010 schedules or reserves a target waketime (TWT) for non-TIM-capable clients, the coexistence controller 1030can also protect the scheduled TWT of the non-TIM-capable clients frombeing preempted by TIM-capable clients. In particular, for implementingthis technique, the coexistence controller 1030 can indicate toTIM-capable clients a restricted access window (RAW) information, duringwhich no TIM-capable clients can occupy the wireless network circuit. Insome embodiments, the RAW information are included in an RPS element inthe beacons sent from the base station 1030. In some embodiments, if theRPS element indicates that the RAW is allocated only to non-TIM-capableclients, then any TIM-capable client that checks the beacon should notaccess the wireless network circuit for the duration indicated by the“RAW Duration” field in the RAW information within the RPS element. Inanother example, if the scheduled TWTs for non-TIM-capable clients areperiodic, then the base station 1030 may set up a periodic RAWoperation, such as defined in Clause 9.19.4a.6 of the IEEE 802.11standards.

In some embodiments, the coexistence controller 1030 can adopt knowntime division multiplexing (TDM) techniques in managing the wirelessnetwork circuits 1020 a-1020 b, and in some embodiments, certain timedurations can be assigned to certain types of data traffic.

FIG. 11 is a timing diagram 1100 for handling downlink traffic from thebase station 1010 to the wireless sensors 1070 a-1070 n of FIG. 10 inaccordance with some embodiments. As shown in diagram 1100, once thebase station 1010 knows that a wireless sensor (e.g., sensor 1070 a)wakes up, the coexistence mechanism in the base station 1010 can givepriority to the downlink traffic to the wireless sensor 1070 a. Thesleep schedule of the wireless sensor 1070 a can be transmitting orbroadcasted using one or more suitable methods including, for example,utilizing beacons to transmit the traffic indication map (TIM) asdescribed in the IEEE 802.11 standards. As such, in some embodiments,the coexistence controller 1030 can determine a reservation schedule inselectively suppressing the transmitting operations based on statussignals received from one or more wireless sensors.

FIG. 12 is a timing diagram 1200 for handling uplink traffic from thewireless sensors 1070 a-1070 n to the base station 1010 of FIG. 10 inaccordance with some embodiments. Similar to diagram 1100, once the basestation 1010 knows that a wireless sensor (e.g., sensor 1070 a) startsto transmit data, the coexistence mechanism in the base station 1010 cangive priority to the uplink traffic from the wireless sensor 1070 a.

FIG. 13 is an abstract diagram 1300 illustrating an asymmetricalbuffering structure or mechanism which can be adopted or controlled bythe coexistence controller in accordance with some embodiments. Morespecifically, among other reasons, because the suppression of thewireless network circuits, and because some wireless network circuitshave higher priority than the others, one or more buffers can beincluded in the base station 1010 (FIG. 10) and coupled to the wirelessnetwork circuits 1020 a-1020 b for temporarily storing data. In some ofthese embodiments, the coexistence controller 1030 (FIG. 10) can beconfigured to allocate more resource in the buffers to the networkcircuit with higher priority (e.g., circuit 1020 b). Such example isillustrated in diagram 1300. In some embodiments, the coexistencecontroller 1030 can also adjust a buffer rate of the buffers based onworkload of the network circuits 1020 a-1020 b.

In some embodiments, the coexistence controller 1030 can also coordinateamong the wireless sensors 1070 a-1070 n so as to cause the wirelesssensors 1070 a-1070 n not to interfere with one another's datatransmission. In some embodiments, the wireless sensors 1070 a-1070 nmay communicate to the coexistence controller 1030 regarding theirrespective battery or other power status, and the coexistence controller1030 can prioritize communication among one or more wireless sensors1070 a-1070 n based on their respective power supply status. Forexample, the coexistence controller 1030 can selectively sendacknowledge (ACK) packets to those wireless sensors among sensors 1070a-1070 n which are low on power so as to avoid them retransmit the data.

Virtual Access Points for Low Power (or Power-Sensitive) Devices

FIG. 16 is an abstract diagram 1600 illustrating a wireless base stationor residential gateway 1610 which implements the power saving techniquessuch as fast channel switching or accurate beacon timing disclosedherein in accordance with some embodiments.

The present embodiments recognize that wireless network technologieshave grown substantially in terms of transmission speed; however, theincrease in transmission speed is typically obtained at the expense ofpower consumption which may adversely affect the operational life ofbattery powered devices, and especially with wireless sensors wherethese sensors are expected to operate on batteries for a long time andare at idle or asleep most of the time. Previous solutions to thisproblem include having, on the base station, a separate radio networkcircuit operating at another frequency band (e.g., 900 MHz) designatedfor connecting the wireless sensors or other power-sensitive deviceswhile having a regular network circuit performing data communicationwith regular clients at regular speed. However, this conventionaltechnique requires separate and designated network circuitry for thepower-sensitive sensors or other devices, and the designated networkcircuitry can create a waste when the base station is not employed in anenvironment with such power-sensitive devices. Further, without theaforementioned coexistence controller mechanisms, conventional basestations typically do not have more than one wireless network circuitoperating in the same frequency band (e.g., 2.4 GHz). It is desirable toprovide methods and apparatuses that reduce power consumption ofpower-sensitive mobile devices (e.g., wireless sensors) while stillsatisfying the need for transmission speed of regular devices for thosedevices that may not have the aforementioned coexistence controller. Itis noted, however, that the disclosed fast channel switching, accuratesensor, beacon and other techniques can be applied to devices with morethan one wireless network circuit operating in the same frequency bandas well as devices with only one wireless network circuit operating in agiven frequency band.

In accordance with some embodiments, the base station 1610 include awireless network circuit 1620, which is capable of connecting wirelesslyto computing devices for data communication using, for example, WirelessLAN technologies at a frequency band (e.g., 2.4 GHz, 5 GHz, etc.). Aspreviously mentioned and shown in FIG. 2C, a frequency band typicallyhas a plurality of channels (e.g., channels 1-11 of the 2.4 GHzfrequency band as shown in FIG. 2C).

According to one or more embodiments, the base station 1610 can utilizethe wireless network circuit 1620 to nearly simultaneously connect toregular (e.g., not power-sensitive) wireless devices 1630 a-1630 n onone channel (e.g., channel X) using regular connections (e.g., standardIEEE 802.11 protocols) while connecting to power-sensitive wirelessdevices (e.g., wireless sensors) 1670 a-1670 n on another channel (e.g.,channel Y) using low-power connections (e.g., modified or adjustedversions of WLAN protocols).

According to the present embodiments, the low-power connection has arelaxed connection maintenance standard than the regular connection. Forexample, the relaxed connection maintenance standard expects to receivekeep alive messages at a frequency less than default. The low-powerconnection may also have a longer keep alive expiration period than theregular connection so that the network device does not disassociate thepower-sensitive client after a regular keep alive expiration periodexpires. So, in one example of the low-power connection, the basestation 1610 may expect sensors to wake up only every N (e.g. 10, 100,or 200) beacons where N may be bigger than the default. In anotherexample, the base station 1610 may not dissociate a sensor simplybecause the sensor has not responded to a transaction (e.g., a Layer 2mechanism, any form of Ping, or other communication sent to the sensor).In yet another example, the base station 1610 can expect Keep Alivemessages to be transmitted less often from the sensors. In someembodiments, the frequency of Keep Alive samples may vary for differentclass of sensors (e.g. smart meter monitors versus camera and other homemonitors).

More specifically, the base station 1610 can include control softwareand/or circuitry (not shown in FIG. 16 for simplicity) that is coupledto the network circuit 1620. In one or more embodiments, the software orcontrol circuitry can be configured so that the base station 1610 is to,upon receipt of a request of connection from a client, identify whetherthe client is power-sensitive. If the client is identified aspower-sensitive, the base station 1610 can cause the power-sensitiveclient to connect using a low-power connection while maintaining aregular connection to other regular clients. More specifically,depending on the embodiment, the base station 1610 can cause thepower-sensitive client to connect in at least one of two ways. In someexamples, the power-sensitive client is connected to the base station1610 directly using the low-power connection (e.g., on channel Y). Insome other examples, the power-sensitive client is first connected tothe base station 1610 using a regular connection similar to the otherregular clients, and then the base station 1610 can switch thepower-sensitive client to the low-power connection (e.g., by switchingfrom channel X to channel Y). In other words, in some examples, the basestation 1610 can configured to connect the power-sensitive client on thelow-power channel. In some other examples, the base station 1610 firstconnects the power-sensitive client on the regular channel, discoverwhether a connected client is power-sensitive, and shift the connectedclient from the regular channel to the low-power channel if theconnected client is power-sensitive. In another embodiment, the basestation 1610 may transmit special beacons for power-sensitive sensors onthe regular channel. The special sensor beacons may be transmitted withmore accurate timing requirements as compared to typical IEEE 802.11beacons.

The low-power connection can be operated on a first channel differentfrom but in a same frequency band as a second channel on which theregular connection is operated. For example, the first channel can bechannel 1 of the 2.4 GHz frequency band, and the second channel can bechannel 11 of the 2.4 GHz frequency band.

Some examples of the power-sensitive clients 1670 a-1670 n can includewireless sensors such as cameras, door bells, passive infrared (PIR)motion sensors, smoke detectors, or other suitable devices. Some devicessuch as pass-through sockets or actuators, which may be a part of thesensor network, can be treated as sensors for purposes of discussionherein. The sensors may be low-powered devices that operate on batteriesand are not designed to be frequently recharged or replaced. As such,these devices are sensitive to power consumption (or power-sensitive)and may largely benefit if special, separate treatment can be given tosave power. These treatments may be different from those regularpower-saving techniques (e.g., IEEE 802.11 compliant) for other regulardevices.

In some embodiments, when the base station 1610 sees no sensor, the basestation 1610 may act as a “regular” WLAN access point. Optionally, thebase station 1610 can broadcast information about its ability oflow-power connection. For example, the base station 1610 can utilizebeacon frames, probe responses, and/or association responses to signalits capabilities. In one embodiment, the base station 1610 signals thelow-power sensor support by having a vendor defined information elementin the beacons.

As previously mentioned, in some embodiments, the power-sensitivedevices (e.g., sensors) 1670 a-1670 n may recognize the low-power,dual-mode capable base station 1610. During the association, wirelesssensor devices can, for example, communicate with the base station 1610so that the base station 1610 knows the client is a power-sensitiveclient, and can react accordingly. More specifically, one or moreembodiments of the base station 1610 can function as two virtual orlogical access points using the same wireless circuit 1620. For example,the base station 1610 can operate a first virtual access point for thelow-power connection, and can operate a second virtual access point forthe regular connection. In some embodiment, the base station 1610 maysend two or more type of beacons on a channel where at least one type ofbeacon is designate to power-sensitive (e.g., sensor) devices. Accordingto some embodiments, the base station 1610 can perform fast channelswitching between the channel that runs regular connections (hereinafteras “regular channels”) and the channel that runs low-power connections(hereinafter as “low-power channels”). In some examples, the first andsecond virtual access points can have different service set identifiers(SSIDs). In other examples, the two virtual access points are only knownto the base station 1610 and the connected devices (e.g., wirelesssensors 1670 a-1670 n). More details of the fast channel switchingtechniques which can be implemented by the base station 1610 are furtherdescribed in conjunction with FIGS. 17A-21B.

FIGS. 17A-17B are example timing diagrams respectively illustratingbeacons sent on two separate channels by the base station 1610 inaccordance with some embodiments. FIG. 17A illustrates an examplebehavior of the base station 1610 when there is no power-sensitiveclient (e.g., wireless sensor) connected to it. FIG. 17B illustrates anexample behavior of the base station 1610 when there is apower-sensitive client connected. According to the present embodiments,the base station 1610 can perform fast channel switching between the twochannels, one for regular connections and one for low-power connections.The periodic signal transmitted on the low-power channel (e.g., ChannelY) maybe done using IEEE 802.11 beacon format or it could be other typeof packet. For example, the period of the beacons for thepower-sensitive sensors on the low-power channel may be different thanthe period of the beacons on the other, regular channel. Specifically,the beacons on the low-power channel can be transmitted in a fashionthat saves power from sensors. The beacon may be shortened to reducepower consumption. However, it is noted that the timing of the beaconsshould be made as accurate as possible. The beacon may includeinformation about indication of downlink traffic or trigger for uplinktraffic. The uplink traffic may be initiated using the beacon or someother suitable means.

FIGS. 17C-17D are example timing diagrams for the embodiments where twoor more types of beacon are transmitted on the same channel and where atleast one type of beacon is designated to the power-sensitive (e.g.,sensor) clients. In some embodiments, the sensor beacons as depicted inFIG. 17C may be shortened in time, and/or they may be transmitted withmechanisms (e.g., as shown in FIG. 17D) that result in more accuratebeacon timing compared to typical IEEE 802.11 beacons. In someimplementations, the sensors can associate with the base station 1610using the IEEE 802.11 beacons and, after the connection is established,the sensors can maintain the connection by listening to the sensorbeacons. In some embodiments, the sensors can maintain the connection bylistening exclusively to the sensor beacons. FIG. 17D illustrates anexample mechanism to improve the timing of sensor beacons. In FIG. 17D,a clear to send to self message, or “CTS2SELF,” is transmitted prior tothe sensor beacons to reserve the medium for the sensor beacons. Bytransmitting the CTS2SELF, the base station 1610 reserves the mediumsuch that the other associated stations in overlapping basic service set(BSS) do not transmit when the sensor beacon is supposed to betransmitted, thereby resulting in a more timing accurate beacon.

Some embodiments of the base station 1610 provide fast channel switchingcapabilities between the two channels so that the connection can appearseamless. In some other embodiments, the base station 1610 can advise onclients connected to one channel (e.g., the channel that runs regularconnections) before it switches to another channel (e.g., the channelthat runs low-power connections) so that those clients connected to thechannel that is which is being switched away temporarily can anticipatethe base station 1610 not listening to the clients' requests/responsesand data during the switch-away period. In accordance with someembodiments, the base station 1610 can also select the channels forregular and low-power connections, respectively, from available channelsbased on one or more connection environment parameters. The connectionenvironment parameters include, by way of example and not limitation,channel noise, channel cross-interference, number of overlapping basicservice sets (OBSS), a number of power-sensitive clients currentlyconnected, or a number of regular clients currently connected. In somealternative examples, the base station 1610 can put power-sensitiveclients and regular clients on the same channel and enable low powersupport for the power-sensitive client on same channel.

FIGS. 18A-18C are example timing diagrams respectively illustratingswitching channels for beacon in the fast channel switching techniquesin accordance with some embodiments.

For the timing of the channel switching, in some embodiments, if thebase station 1610 is the owner of the transmission operation (TXOP) (forexample, if the base station 1610 is transmitting downlink traffic to aregular client, or if the base station 1610 is transmitting control ormanagement frame), then the base station 1610 can switch at the time ofbeacons. If the link is idle, then some embodiments of the base station1610 simply switches when needed.

As mentioned, when the base station 1610 switches channel, the basestation 1610 can send a packet to announce to those clients connected onthe channels that is being switched away that it is not present. In someembodiments, the PKTX packet can be used in announcing the absence onchannel X, such as illustrated in FIGS. 18A-18B. The PKTX packet can bea serial clear to send to self (CTS2SELF) message. It is noted that, inother embodiments, mechanisms defined in IEEE 802.11v, WiFi notice ofabsence, or other suitable mechanisms can also be used.

In some examples, the base station 1610 can simply switch channelswithout advance announcement, such as illustrated in FIG. 18C. However,it is noted that, while the implementation of switching withoutannouncement may be simpler, the regular clients may perform retriessince they would not know, at least initially, that the base station1610 has switched away to another channel.

FIGS. 19A-19B are example timing diagrams respectively illustratingresource reservation by sensors in the fast channel switching techniquesin accordance with some embodiments.

In some examples, the power-sensitive client or sensor can have definedtime in which the client can announce to the base station 1610 that ithas uplink traffic to send, and the base station 1610 may adjust thetime the base station 1610 spends on each channel based on theannouncement which indicates when the wireless sensor needs to transmitits uplink data traffic to the base station 1610.

Specifically, the base station 1610 can receive information from thepower-sensitive client so as to anticipate when there is data trafficfrom the power-sensitive client, and the base station 1610 can adjustthe timing and network circuits based on the anticipation. Moreover, insome embodiments, the base station 1610 can receive information from thepower-sensitive client regarding what resource the power-sensitiveclient needs for transmitting data traffic to the network device, andthe base station 1610 can arrange a time slot based on the information.Then, the base station 1610 can convey information to thepower-sensitive client regarding the time slot.

So for example, a wireless sensor can communicate to the base station1610 that it has uplink traffic to transmit. Additionally, the wirelesssensor may communicate the bandwidth requirement in a defined timingrelative to every X beacon. As illustrated in FIG. 19A, every X beaconinterval, there can be some window of time where the wireless sensor cantell the base station 1610 that it has uplink traffic. The sensor canstart contending for the medium during that window of time, and when thesensor gets the medium, it can start transmitting the uplink traffic.Additionally or alternatively, there can be a schedule resourcereservation interval. The scheduled time interval is defined relative toevery X beacon, such as illustrated in FIG. 19B. Then, the base station1610 can tell the sensor (e.g. camera) about when it should transmit theuplink traffic.

In some embodiments, the base station 1610 can switch, for data trafficfrom the power-sensitive client, the power-sensitive client from thelow-power channel to the regular channel for the duration of thetraffic. Some embodiments of the base station 1610 also include a bufferconfigured to accommodate an uplink transmission rate slower than thatof the regular connection from the power-sensitive client. In addition,the base station 1610 can receive information from the power-sensitiveclient regarding a wake-up schedule of the power-sensitive client. Thewake-up schedule can indicate that the power-sensitive client wakes upless frequently than a regular client. For example, the power-sensitiveclient may only wake up every X beacons, where X is larger than default.

In general, the base station 1610 gives priority to the power-sensitiveclient when there is data traffic from the power-sensitive client. Inparticular, many embodiments of the base station 1610 gives absolutepriority to the beacon timing for the wireless sensors (on the low-powerchannel) over anything taking place on the regular clients (on theregular channel). However, to avoid regular client starvation or othersuitable reasons, one or more embodiments of the base station 1610 canbe adjusted so that priority is given to power-sensitive clients every 1out of M beacons, where M can be a predetermined number based onexperience, experiments, or can be dynamically adjusted based on theexperienced traffic.

FIG. 20 is an example timing diagrams illustrating downlink trafficoperations from the base station to the sensors in the fast channelswitching techniques in accordance with some embodiments.

For downlink operations, in some embodiments, sensor downlink traffic(i.e., from the base station 1610 to the sensor) can be transmitted onthe low-power channel. In some other embodiments, the downlink trafficmay be transmitted on the regular channel. In FIG. 20, an example forU-APSD is illustrated; however, it is noted that PS-POLL, U-APSD, orboth may be used.

FIGS. 21A-21B are example timing diagrams respectively illustratinguplink traffic operations from the sensors to the base station in thefast channel switching techniques in accordance with some embodiments.

In some embodiments, sensor uplink traffic (i.e., from the sensor to thebase station 1610) can be transmitted on the low-power channel, such asillustrated in FIGS. 21A-21B. When a wireless sensor finishestransmitting the last packet in a burst, the sensor can signal the basestation 1610 that the transmission is complete, at which time the basestation 1610 can make a determination as whether and when the basestation 1610 should switch channel (e.g., back to the regular channel).As illustrated in the example of FIG. 20A, an EOSP bit may be used tosignal the end of the burst. Additionally or alternatively, a RTS/CTShandshake can be performed between the base station 1610 and thewireless sensor before the sensor starts to transmit uplink data, suchas illustrated in FIG. 21B.

In some embodiments, the base station 1610 may poll the sensors and askthem if they have any uplink traffic to send. Additionally, if the basestation 1610 is expecting a sensor to transmit an uplink packet, thebase station 1610 may poll the sensor to transmit the uplink packet.Further, one embodiment provides that, if the sensor does not transmitthe packets in response to the poll, the base station 1610 can choose tomove on to communicate with the other sensors, or the base station 1610may switch to the other channel.

FIGS. 22A-22B are additional or alternative example timing diagramsrespectively illustrating uplink operations in the fast channelswitching techniques in accordance with some embodiments. In theexamples of FIGS. 22A-22B, the regular channel is used to transmit thesensor uplink traffic.

First, as illustrated in FIG. 22A, the sensor beacon indicates that asensor (e.g. camera has uplink data to transmit. Then, the sensorswitches to the regular channel (e.g., Channel X) and start contendingfor the medium. After the sensor acquires the medium, the sensor starttransmitting. At the end of the transmission, the base station 1610switches back to the low-power channel (e.g., Channel Y) and keeplistening sensor beacons. Additionally or alternatively, a RTS/CTShandshake can be performed between the base station 1610 and thewireless sensor before the sensor starts to transmit uplink data, suchas illustrated in FIG. 22B. It is noted that, in FIGS. 22A-22B, thesensor can decide whether to transmit uplink packet based on timer,events, or other parameters.

Methodology

FIG. 14 is a flowchart illustrating a method 1400 for controlling andcoordinating multiple radio circuits which can be implemented by acoexistence controller (e.g., controller 230, FIG. 2) in accordance withsome embodiments. The method 1400 is performed, for example, in a basestation (e.g., station 210, FIG. 2).

In one or more embodiments, each of a plurality of network circuits(e.g., circuits 220 a-220 c) located on the station 210 can be assigned(1410) a priority. In some embodiments, the coexistence controller 230is coupled to the network circuits 220 a-220 c through a coexistence bus(e.g., bus 240, FIG. 2) to control operations between (or among) thenetwork circuits 220 a-220 c. More specifically, the priority eachnetwork circuit can be predetermined by the manufacturer of the basestation 210, or the priority can be optionally and/or dynamicallyassigned (1410) by the coexistence controller 230 based on certainpriority assigning criteria. The priority assigning criteria may includethe amount of traffic, the type of traffic (e.g., data, voice, video,sensor applications, etc.), wireless channel conditions each circuitexperiences, and/or other suitable factors. As explained above, thepriority assigning criteria may be similar to operating criteria.

Then, the coexistence controller 230 can determine (1420) a plurality ofoperating criteria based on the priority assigned to each networkcircuit as well as other factors. The operating criteria can reflect avariety of considerations such as the number of client devices (e.g.,devices 130, FIG. 1) each network circuit handles, the amount of datatraffic each network circuit sees, the data rate each network circuitsupports, the type of traffic each network circuit is assigned, thewireless channel condition or noise (e.g., as measured by RSSI or aknown matrix rank) each network circuit experiences, and so forth.According to the present embodiments, the operating criteria areselected to cause the coexistence controller to control the operationsin a way that reduces a probability that network circuits 220 a-220 cdesensitize one another. In some embodiments, the operating criteria areselected in a way such that the coexistence controller 230 can perform,for example, load balancing and/or frequency planning using multiplewireless network circuits (e.g., circuits 220 a-220 c) on base station210.

Next, the coexistence controller 230 can control (1430) operationsbetween the network circuits by selectively adjust one or moretransmission operating parameters of a respective network circuit (e.g.,circuit 220 a) based on a plurality of operating criteria includingnetwork circuit 220 a's priority as compared to other circuits'priorities.

The transmission operating parameters for a wireless network circuit isthe configurations in which the network circuit uses to transmit data.For example, in some embodiments, the coexistence controller 230 canreduce the transmit power on one wireless network circuit (e.g., circuit220 a) when another wireless network circuit (e.g., circuit 220 b) isreceiving. In additional or alternative embodiments, other transmissionoperating parameters that can be adjusted by the coexistence controller230 can include a data rate (e.g., 11 Mbit/s, or 54 Mbit/s) and/or anetwork protocol (e.g., IEEE 802.11a, IEEE 802.11n, etc.) at which therespective network circuit operates. In some examples, the transmissionoperating parameters can also include a channel (e.g., channel 1,channel 6, or channel 11 in WLAN 2.4 GHz frequency band; or channel 36,channel 100, or channel 161 in WLAN 5 GHz frequency band) on which therespective network circuit operates. In some embodiments, thetransmission operating parameters can also include a frequency band(e.g., 2.4 GHz, 5 GHz, etc.) in which the respective network circuitoperates. Other known configuration adjustments such as modulation orphase adjustments can also be included in the list of transmissionoperating parameters which the coexistence controller 230 can adjust.

FIG. 15 is a flowchart illustrating a method 1500 for reducinginterference among multiple radio circuits which can be implemented by acoexistence controller (e.g., controller 1030, FIG. 10) in accordancewith some embodiments. The method 1500 is performed, for example, in abase station (e.g., station 1010, FIG. 10).

First, in some optional embodiments, the controller 1030 can supportclient devices or sensors that can transmit traffic indication maps(TIM), and the coexistence controller 1030 can arrange or determine(1510) traffic scheduling and give priority to a respective wirelesscircuit based on the received TIM information. For the client devices orwireless sensors that do not have TIM capacity, when the base station1010 schedules or reserves a target wake time (TWT) for non-TIM-capableclients, the coexistence controller 1030 can also protect the scheduledTWT of the non-TIM-capable clients from being preempted by TIM-capableclients. In particular, for implementing this technique, the coexistencecontroller 1030 can indicate to TIM-capable clients a restricted accesswindow (RAW) information, during which no TIM-capable clients can occupythe wireless network circuit.

In accordance with some embodiments, the coexistence controller 1030 cancause the wireless circuits (e.g., 1020 a and 1020 b) coupled to thestation 1030 to operate in ways that do not cause interference ordesensitization to one another. More specifically, the coexistencecontroller 1030 can utilize the coexistence mechanisms (e.g., asmentioned above) to give priority to those data communications from thevarious wireless sensors 1070 a-1070 n by selectively suppressing (1520)the transmitting operations of the wireless network circuit 1020 aduring the receiving operations of the wireless network circuit 1020 b,when the network circuit 1020 b is assigned (1524) a higher prioritythan the network circuit 1020 a. The plurality of network circuitsoperate (1522) in a same radio frequency band and are collocated (1522).

For example, the coexistence controller 1030 can suppress thetransmission communication by disabling, postponing, attenuating thepower level used in, reducing transmission rate of, or applying anyother operating parameter adjustment techniques discussed herein onto,the transmission operations. In this way, the coexistence controller1010 is able to suppress (1520) the transmitting operations of thenetwork circuit 1020 a in a way that maintains integrity of receivingoperations of the network circuits 1020 b (e.g., so that the receivingis not disrupted or corrupted). It is noted that some embodiments of thewireless network circuits 1020 a-1020 b operate on different channels(e.g., channels 1 and 6).

FIG. 23 is a flowchart illustrating a method 2300 for enabling a basestation to distinguish power-sensitive devices and provide separatetreatment thereto in accordance with some embodiments. The method 2300is performed, for example, in a base station (e.g., station 1610, FIG.16).

According to one or more embodiments, the base station 1610 can utilizethe wireless network circuit 1620 to nearly simultaneously connect toregular (e.g., not power-sensitive) wireless devices 1630 a-1630 n onone channel (e.g., channel X) using regular connections (e.g., standardIEEE 802.11 protocols) while connecting or maintaining connection topower-sensitive wireless devices (e.g., wireless sensors) 1670 a-1670 non another channel (e.g., channel Y) using low-power connections (e.g.,modified versions of WLAN protocols). The low-power connection has arelaxed connection maintenance standard than the regular connection. Forexample, the relaxed connection maintenance standard expects to receivekeep alive messages at a frequency less than default. The low-powerconnection may also have a longer keep alive expiration period than theregular connection so that the network device does not disassociate thepower-sensitive client after a regular keep alive expiration periodexpires.

The base station 1610 can include control circuitry or software (notshown in FIG. 16 for simplicity) that is coupled to the network circuit1620. In one or more embodiments, the control circuitry can beconfigured so that the base station 1610 is to, upon receipt of arequest of connection from a client, identify (2310) whether the clientis power-sensitive. If the client is identified as power-sensitive, thebase station 1610 can cause (2320) the power-sensitive client to connectusing a low-power connection while maintaining a regular connection toother regular clients. More specifically, depending on the embodiment,the base station 1610 can cause the power-sensitive client to connect inat least one of two ways. In some examples, the power-sensitive clientis connected to the base station 1610 directly using the low-powerconnection (e.g., on channel Y). In some other examples, thepower-sensitive client is first connected to the base station 1610 usinga regular connection similar to the other regular clients, and then thebase station 1610 can switch the power-sensitive client to the low-powerconnection (e.g., by switching from channel X to channel Y). In otherwords, in some examples, the base station 1610 can configured to connectthe power-sensitive client on the low-power channel. In some otherexamples, the base station 1610 first connects the power-sensitiveclient on the regular channel, discover whether a connected client ispower-sensitive, and shift the connected client from the regular channelto the low-power channel if the connected client is power-sensitive.

The low-power connection can be operated (2325) on a first channeldifferent from but in a same frequency band as a second channel on whichthe regular connection is operated. For example, the first channel canbe channel 1 of the 2.4 GHz frequency band, and the second channel canbe channel 11 of the 2.4 GHz frequency band.

FIG. 24 is a flowchart illustrating additional or alternative details ofthe method 2300 of FIG. 23. In particular, some of the control andmanagement used (2327) for the power-sensitive devices can be differentthan the regular, non-power-sensitive devices. The packets that aredifferent can include, by way of example but not limitation, specialbeacons for the power-sensitive devices (e.g., as described above). Thespecial beacons designated for the power-sensitive devices may be moreaccurate in timing and/or may be shorter.

CONCLUSION

In the foregoing specification, the present embodiments have beendescribed with reference to specific exemplary embodiments thereof. Itwill, however, be evident that various modifications and changes may bemade thereto without departing from the broader scope of the disclosureas set forth in the appended claims. The specification and drawings are,accordingly, to be regarded in an illustrative sense rather than arestrictive sense.

It should also be understood that all block diagrams in the figures arefor illustration purpose only, and should not preclude the scope of thisinvention to include any logic equivalents or combinations thereof,including removing, substituting, or adding other logic gates thatachieves the same or similar functions consistent with the features ofthe present invention.

Further, it should be noted that the various circuits disclosed hereinmay be described using computer aided design tools and expressed (orrepresented), as data and/or instructions embodied in variouscomputer-readable media, in terms of their behavioral, registertransfer, logic component, transistor, layout geometries, and/or othercharacteristics. Formats of files and other objects in which suchcircuit expressions may be implemented include, but are not limited to,formats supporting behavioral languages such as C, Verilog, and VHDL,formats supporting register level description languages like RTL, andformats supporting geometry description languages such as GDSII, GDSIII,GDSIV, CIF, MEBES and any other suitable formats and languages.Computer-readable media in which such formatted data and/or instructionsmay be embodied include, but are not limited to, non-volatile storagemedia in various forms (e.g., optical, magnetic or semiconductor storagemedia).

What is claimed is:
 1. A network device, comprising: control circuitrycoupled to one or more wireless network circuits and configured to: uponreceipt of a request of connection from a client, identify whether theclient is power-sensitive; and if the client is identified aspower-sensitive, cause the power-sensitive client to connect using alow-power connection while maintaining a regular connection to otherregular clients, wherein the low-power connection has a relaxedconnection maintenance standard than the regular connection, and whereinthe relaxed connection maintenance standard expects to receive keepalive messages at a frequency less than default.
 2. The network deviceof claim 1, wherein the low-power connection is operated on a firstchannel different from but in a same frequency band as a second channelon which the regular connection is operated, and wherein the controlcircuitry is further configured to: switch, for data traffic from thepower-sensitive client, the power-sensitive client from the firstchannel to the second channel for a duration of the traffic.
 3. Thenetwork device of claim 1, wherein the low-power connection is operatedon a first channel different from but in a same frequency band as asecond channel on which the regular connection is operated, and whereinthe control circuitry is further configured to: discover whether aconnected client is power-sensitive; and shift the connected client fromthe second channel to the first channel if the connected client ispower-sensitive.
 4. The network device of claim 1, wherein the low-powerconnection is operated on a first channel different from but in a samefrequency band as a second channel on which the regular connection isoperated, and wherein the client is initially connected to the networkdevice on the second channel.
 5. The network device of claim 1, whereinthe control circuitry is further configured to: operate a first virtualaccess point (AP) for the low-power connection; and operate a secondvirtual AP for the regular connection, wherein the first and second APsuse different service set identifiers (SSIDs).
 6. The network device ofclaim 1, wherein the control circuitry is further configured to: receiveinformation from the power-sensitive client so as to anticipate whenthere is data traffic from the power-sensitive client; and adjust thenetwork circuits based on the anticipation.
 7. The network device ofclaim 1, wherein the control circuitry is further configured to: receiveinformation from the power-sensitive client regarding what resource thepower-sensitive client needs for transmitting data traffic to thenetwork device; arrange a time slot based on the information; and conveyinformation to the power-sensitive client regarding the time slot. 8.The network device of claim 1, wherein the control circuitry is furtherconfigured to: give priority to the power-sensitive client when there isdata traffic from the power-sensitive client.
 9. The network device ofclaim 1, wherein the low-power connection is operated on a first channeldifferent from but in a same frequency band as a second channel on whichthe regular connection is operated, and wherein the first channel isemployed by a network circuit different from a second network circuit bywhich the second channel is employed.
 10. The network device of claim 1,further comprising: a buffer configured to accommodate a uplinktransmission rate slower than that of the regular connection from thepower-sensitive client.
 11. The network device of claim 1, wherein thecontrol circuitry is further configured to: broadcast information aboutthe network device's ability of low-power connection.
 12. The networkdevice of claim 1, wherein the control circuitry is further configuredto: receive information from the power-sensitive client regarding awake-up schedule of the power-sensitive client.
 13. The network deviceof claim 1, wherein the low-power connection is operated on a firstchannel different from but in a same frequency band as a second channelon which the regular connection is operated.
 14. The network device ofclaim 1, wherein the low-power connection has a longer keep aliveexpiration period than the regular connection so that the network devicedoes not disassociate the power-sensitive client after a regular keepalive expiration period expires.
 15. The network device of claim 1,wherein the low-power connection is operated on a first channeldifferent from but in a same frequency band as a second channel on whichthe regular connection is operated, and wherein the control circuitry isfurther configured to: select the first and second channels,respectively, from available channels based on one or more connectionenvironment parameters.
 16. The network device of claim 14, wherein theconnection environment parameters include one or more of: channel noise,channel cross-interference, number of overlapping basic service sets(OBSS), a number of power-sensitive clients currently connected, or anumber of regular clients currently connected.
 17. A method, comprising:upon receipt of a request of connection from a client, identifying,using a network device, whether the client is power-sensitive; and ifthe client is identified as power-sensitive, causing the power-sensitiveclient to connect using a low-power connection while maintaining aregular connection to other regular clients, wherein the low-powerconnection has a longer keep alive expiration period than the regularconnection so that the network device does not disassociate thepower-sensitive client after a regular keep alive expiration periodexpires.
 18. The method of claim 16, wherein the low-power connection isoperated on a first channel different from but in a same frequency bandas a second channel on which the regular connection is operated, themethod further comprising: switching, for data traffic from thepower-sensitive client, the power-sensitive client from the firstchannel to the second channel for a duration of the traffic.
 19. Themethod of claim 16, wherein the low-power connection is operated on afirst channel different from but in a same frequency band as a secondchannel on which the regular connection is operated, the method furthercomprising: discovering whether a connected client is power-sensitive;and shifting the connected client from the second channel to the firstchannel if the connected client is power-sensitive, wherein the clientis initially connected to the network device on the second channel. 20.The method of claim 16, further comprising: operating a first virtualaccess point (AP) for the low-power connection; and operating a secondvirtual AP for the regular connection, wherein the first and second APsuse different service set identifiers (SSIDs).
 21. The method of claim16, further comprising: receiving information from the power-sensitiveclient so as to anticipate when there is data traffic from thepower-sensitive client; and adjusting the network circuits based on theanticipation.
 22. The method of claim 16, further comprising: receivinginformation from the power-sensitive client regarding what resource thepower-sensitive client needs for transmitting data traffic to thenetwork device; arranging a time slot based on the information; andconveying information to the power-sensitive client regarding the timeslot.
 23. The method of claim 16, further comprising: giving priority tothe power-sensitive client when there is data traffic from thepower-sensitive client.
 24. A network device, comprising: controlcircuitry coupled to one or more wireless network circuits andconfigured to: upon receipt of a request of connection from a client,identify whether the client is power-sensitive; and if the client isidentified as power-sensitive, cause the power-sensitive client toconnect using a low-power connection while maintaining a regularconnection to other regular clients, wherein the low-power connectionhas a longer keep alive expiration period than the regular connection sothat the network device does not disassociate the power-sensitive clientafter a regular keep alive expiration period expires.
 25. The device ofclaim 24, wherein the low-power connection is operated on a firstchannel different from but in a same frequency band as a second channelon which the regular connection is operated, the control circuitryfurther configured to: switch, for data traffic from the power-sensitiveclient, the power-sensitive client from the first channel to the secondchannel for a duration of the traffic.
 26. The device of claim 24,wherein the low-power connection is operated on a first channeldifferent from but in a same frequency band as a second channel on whichthe regular connection is operated, the control circuitry furtherconfigured to: discover whether a connected client is power-sensitive;and shift the connected client from the second channel to the firstchannel if the connected client is power-sensitive, wherein the clientis initially connected to the network device on the second channel. 27.The device of claim 24, the control circuitry further configured to:operate a first virtual access point (AP) for the low-power connection;and operate a second virtual AP for the regular connection, wherein thefirst and second APs use different service set identifiers (SSIDs). 28.The device of claim 24, the control circuitry further configured to:receive information from the power-sensitive client so as to anticipatewhen there is data traffic from the power-sensitive client; and adjustthe network circuits based on the anticipation.
 29. The device of claim24, the control circuitry further configured to: receive informationfrom the power-sensitive client regarding what resource thepower-sensitive client needs for transmitting data traffic to thenetwork device; arrange a time slot based on the information; and conveyinformation to the power-sensitive client regarding the time slot. 30.The device of claim 24, the control circuitry further configured to:give priority to the power-sensitive client when there is data trafficfrom the power-sensitive client.
 31. A network device, comprising:control circuitry coupled to one or more wireless network circuits andconfigured to: upon receipt of a request of connection from a client,identify whether the client is power-sensitive; and if the client isidentified as power-sensitive, cause the power-sensitive client toconnect using a low-power connection while maintaining a regularconnection to other regular clients, operate a first virtual accesspoint (AP) for the low-power connection; and operate a second virtual APfor the regular connection, wherein the first and second APs usedifferent service set identifiers (SSIDs).
 32. The network device ofclaim 31, wherein the control circuitry is further configured to:switch, for data traffic from the power-sensitive client, thepower-sensitive client from the first channel to the second channel fora duration of the traffic.
 33. The network device of claim 31, whereinthe control circuitry is further configured to: discover whether aconnected client is power-sensitive; and shift the connected client fromthe second channel to the first channel if the connected client ispower-sensitive.
 34. The network device of claim 31, wherein the clientis initially connected to the network device on the second channel. 35.The network device of claim 31, wherein the control circuitry is furtherconfigured to: receive information from the power-sensitive client so asto anticipate when there is data traffic from the power-sensitiveclient; and adjust the network circuits based on the anticipation. 36.The network device of claim 31, wherein the control circuitry is furtherconfigured to: receive information from the power-sensitive clientregarding what resource the power-sensitive client needs fortransmitting data traffic to the network device; arrange a time slotbased on the information; and convey information to the power-sensitiveclient regarding the time slot.
 37. The network device of claim 31,wherein the control circuitry is further configured to: give priority tothe power-sensitive client when there is data traffic from thepower-sensitive client.
 38. The network device of claim 31, wherein thefirst channel is employed by a network circuit different from a secondnetwork circuit by which the second channel is employed.
 39. The networkdevice of claim 31, further comprising: a buffer configured toaccommodate a uplink transmission rate slower than that of the regularconnection from the power-sensitive client.
 40. The network device ofclaim 31, wherein the control circuitry is further configured to:broadcast information about the network device's ability of low-powerconnection.
 41. The network device of claim 31, wherein the controlcircuitry is further configured to: receive information from thepower-sensitive client regarding a wake-up schedule of thepower-sensitive client.
 42. The network device of claim 31, wherein thelow-power connection has a relaxed connection maintenance standard thanthe regular connection, and wherein the relaxed connection maintenancestandard expects to receive keep alive messages at a frequency less thandefault.
 43. The network device of claim 31, wherein the low-powerconnection has a longer keep alive expiration period than the regularconnection so that the network device does not disassociate thepower-sensitive client after a regular keep alive expiration periodexpires.
 44. The network device of claim 31, wherein the controlcircuitry is further configured to: select the first and secondchannels, respectively, from available channels based on one or moreconnection environment parameters.
 45. The network device of claim 44,wherein the connection environment parameters include one or more of:channel noise, channel cross-interference, number of overlapping basicservice sets (OBSS), a number of power-sensitive clients currentlyconnected, or a number of regular clients currently connected.